I am examining the difference in illness models (by asking several questions: DV) for refugees and non-refugees (IV). In addition, we asked about several confounding variables / covariates (demographic data).
Some items of my dataset do not fulfil the requirement of homogeneity of regression slops. I was wandering how I can best describe the relationship of the covariate and DV for those items. I am aware that if I use a MANCOVA/ANCOVA regardless of this assumption violation, this will increase the TYPE II Error.
I have read about Johnson Neyman procure. It seems complicated to me.
Can I calculate a regulare MANOVA/ANOVA for thes items, that do not fulfil the assumption of homogeneity of regression slopes (not enter the covariate)? And then check the way the covariate influences the DV by doing a regression?
I am not aware of a valid method. Does anyone have experience with heterogeneity of regression slopes?
Thank you for your help
K.T.
